Method and system for modeling and advertising asymmetric topology of a node in a transport network

ABSTRACT

A method and system for providing an internal topology of a node within a network includes determining asymmetric connections between traffic bearing components in a network node. An intranode connectivity is determined between the traffic bearing components based on the asymmetric connections. A model of the node indicative of the intranode connectivity is distributed to a disparate node in a network with a node. The model is used at a disparate node in determining a routing path through the network.

RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application Ser.No. 60/202,190, entitled INTERNET PROTOCOL TRANSPORT, filed May 5, 2000which is hereby incorporated by reference.

TECHNICAL FIELD OF THE INVENTION

The present invention relates generally to the field oftelecommunication networks, and more particularly to a method and systemfor modeling and advertising an asymmetric topology of a node in atransport network.

BACKGROUND OF THE INVENTION

Telecommunication networks transport voice and data according to avariety of standards and using a variety of technologies. Circuit-switchnetworks such as plain old telephone service (POTS) utilize transmissionpaths dedicated to specific users for the duration of a call and employcontinuous, fixed-bandwidth transmission. Packet-switch networks (PSNs)allow dynamic bandwidth, depending on the application, and can bedivided into connectionless networks with no dedicated paths andconnection-oriented networks with virtual circuits having dedicatedbandwidth along a predetermined path. Because packet-switched networksallow traffic from multiple users to share communication links, thesenetworks utilize available bandwidth more efficiently thancircuit-switched networks.

Internet protocol (IP) networks are connectionless packet-switchednetworks. IP networks transport information by breaking up bitstreamsinto addressable digital packets. Each IP packet includes source anddestination addresses and can take any available route between thesource and the destination. The IP packets are transmitted independentlyand then reassembled in the correct sequence at the destination.

SUMMARY OF THE INVENTION

The present invention provides a method and system for modeling andadvertising asymmetric topology of a node in a transport network.

In accordance with one embodiment of the present invention, a method forproviding an internal topology of a node within a network includesdetermining asymmetric connections between traffic bearing components ina network node. An intranode connectivity is determined between thetraffic bearing components based on the asymmetric connections. A modelof the node indicative of the intranode connectivity is distributed to adisparate node in a network with the node. The model is used at thedisparate node in determining a routing path through the network.

More specifically, in accordance with a particular embodiment of thepresent invention, the traffic bearing components may comprise receivertransmitter pairs (RTPs) and lower speed interfaces to external nodescoupled to the network. The node model may be distributed using opaquelink state advertisements (LSAs). In addition, the intranodeconnectivity between the traffic bearing components may be determined byassigning weights to the asymmetric connections based on their speeds.

Technical advantages of one or more embodiments of the present inventioninclude providing an improved transport network. In a particularembodiment, the transport network provides a flexible node topology.Asymmetric intranode connectivity may be modeled and advertised withinthe transport network and used for internal routing in the network.

Another technical advantage of one or more embodiments of the presentinvention includes providing an improved Internet protocol transportnode for the transport network. In particular, the transport node isoperable to identify links between internal components and determinepossible connectivity between the components based on the links.Connectivity may be modeled and advertised in opaque link stateadvertisements (LSAs) across the network to support path selectionthrough the asymmetric links.

Other technical advantages of the present invention will be readilyapparent to one skilled in the art from the following figures,description, and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention and itsadvantages, reference is now made to the following description taken inconjunction with the accompanying drawings, wherein like referencenumerals represent like parts, in which:

FIG. 1 is a block diagram illustrating a transport network in accordancewith one embodiment of the present invention;

FIG. 2 is a block diagram illustrating an external representation forthe transport router of FIG. 1 in accordance with one embodiment of thepresent invention;

FIG. 3 is a block diagram illustrating details of the Internet protocoltransport (IPT) node of FIG. 1 in accordance with one embodiment of thepresent invention;

FIG. 4 is a block diagram illustrating details of thereceiver-transmitter pair (RTP) of FIG. 3 in accordance with oneembodiment of the present invention;

FIG. 5 is a block diagram illustrating details of the processing systemof FIG. 3 in accordance with one embodiment of the present invention;

FIG. 6 is a block diagram illustrating distribution of functionalitybetween processors in an exemplary network in accordance with oneembodiment of the present invention;

FIG. 7 is a block diagram illustrating details of the transport networklayer one (IPTL1) architecture for the processing system of FIG. 5 inaccordance with one embodiment of the present invention;

FIG. 8 is a block diagram illustrating details of the transport elementlayer two (IPTL2) architecture for the processing system of FIG. 5 inaccordance with one embodiment of the present invention;

FIG. 9 is a flow diagram illustrating a method for determining andadvertising an asymmetric topology of a node in a transport network inaccordance with one embodiment of the present invention;

FIG. 10 is a flow diagram illustrating a method for provisioning an IPTnetwork in accordance with one embodiment of the present invention;

FIG. 11 is a flow diagram illustrating a method for defining a transportrouter in an IPT network in accordance with one embodiment of thepresent invention;

FIG. 12 is a flow diagram illustrating a method for generating routingtables for a transport router in accordance with one embodiment of thepresent invention; and

FIG. 13 is a flow diagram illustrating a method for processing throughtraffic in a transport router in accordance with one embodiment of thepresent invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 illustrates a transport network 10 in accordance with oneembodiment of the present invention. In this embodiment, the transportnetwork 10 is an Internet protocol (IP) network for transporting IP andMultiple Protocol Label Switch (MPLS) packets. The transport network 10may be any other packet-switched network operable to route, switch,and/or otherwise direct data packets based on network protocoladdresses.

The transport network 10 is a private network connecting geographicallydistributed segments of an external network 12. The external network 12includes one or more public and/or private networks such as theInternet, an intranet, and other suitable local area networks (LAN),wide area networks (WAN), and nodes. The external network 12 includeslabel switch and subtending routers 14, Ethernet switches 16, FrameRelay switches 18 and other suitable routers, switches, and nodesoperable to generate and/or transport traffic. The transport network 10communicates with nodes of the external network 12 in the nativeprotocol of the nodes to communicate traffic and control signalingbetween the networks 10 and 12.

Referring to FIG. 1, the transport network 10 includes a plurality ofInternet protocol transport (IPT) nodes 30 interconnected bycommunication links 32. The IPT nodes 30 each include a plurality ofports 34 accessible to the external network 12. As used herein, eachmeans every one of at least a subset of the identified items. Thecommunication links 32 are optical fiber or other suitable high-speedlinks. The high-speed links are operable to transport traffic at a rateof 5 Gb/s or greater. Preferably, the high-speed links 32 transporttraffic at rates of 10 Gb/s or above.

As described in more detail below, the high-speed links 32 connect highspeed interfaces of the IPT nodes 30 to form fast transport segments(FTS) through the transport network 10. Packets transferred via the FTSsincur very small buffering delay in the network as described in co-ownedU.S. patent application entitled “Method and System for TransportingTraffic in a Packet-Switched Network”, filed Jun. 6, 2000. Packetscarried through the ports 34 and between FTSs may incur queuing delaycomparable to a normal IP switch.

To optimize bandwidth usage within the transport network 10, packets maybe transmitted directly on the high-speed optical links 32 withoutsynchronous optical network (SONET) framing and its associated overheadwhich imposes a penalty of three to five percent depending on the linerate. In one embodiment, a transport label is added to each packet togenerate an internal packet that can be directly transmitted on theoptical links 32. Details of the transport label are described inco-owned U.S. patent application entitled “System and Method forConnectionless/Connection Oriented Signal Transport”, filed Jun. 6,2000. Using the transport label, both connection-oriented andconnectionless traffic may be seamlessly transported across thetransport network 10. Protection for connection oriented data flows maybe provided as described in co-owned U.S. patent application entitled“Method and System For Providing A Protection Path ForConnection-Oriented Signals In A Telecommunications Network”, filed Jun.6, 2000. Protection for connectionless, packet transport, traffic flowsmay be provided as described in co-owned U.S. patent application “Methodand System For Providing A Protection Path For Connectionless Signals InA Telecommunications Network”, filed Jun. 6, 2000.

To support voice, video, and other real-time or time-sensitiveapplications, the transport network 10 may provide class of service(CoS) capabilities. In one embodiment, all IP packets are mapped to oneof three priority levels as they enter the transport network 10. In thisembodiment, guaranteed traffic has reserved bandwidth and is guaranteedto be transported within a defined time delay. Control flow traffic isalso reserved and guaranteed, but the network 10 does not guaranteedelivery time delay. Best effort traffic does not have reservedbandwidth and delivery is not guaranteed by the network 10. Bydistinguishing and prioritizing traffic based on its type, includingCoS, service level agreement (SLA) and/or other suitable indication ofimportance or delivery constraints. The transport network 10 is able todeliver time-sensitive traffic within tight time constraints by delayingand/or dropping best effort traffic and other low priority traffic.

In one embodiment, the transport network 10 utilizes a private internaladdressing scheme to isolate the network 10 from customers and thusminimize or prevent conflicts with private and/or public networksconnected to the transport network 10. This reduces the complexity ofnetwork management and preserves the topology of the existing routednetwork 12. In addition, transport network isolation enables value addedservices to be provided through the transport network 10.

When an independent addressing scheme is utilized for the transportnetwork 10, egress traffic is converted from the external addressingscheme to the internal addressing scheme at ports 34 using standardizedor extended network address translation (NAT). Similarly, egress trafficis converted from the internal addressing scheme back to the externaladdressing scheme at ports 34 using standard or extended NAT. Inaddition to the internal addresses, each IPT node 30, port 34 and othercomponent of the transport network 10 visible to the external network 12includes a globally unique IP address. These addresses are used forexternal management of the transport network 10.

The transport network 10 provides a flexible topology in which sets ofports 34 may be grouped in any suitable way and each treated as a singleentity capable of independently interacting with external nodes. Thus,the transport network 10 is externally represented as sets of portgroups 50 with internally managed connectivity. Provisioning of portgroups 50 in the transport network 10 is unconstrained with mesh andpartial-mesh topologies supported.

The port groups 50 are each a set of ports 34 with similar routingproperties. In particular, a port group 50 is a set of ports 34configured to provide multipoint-to-multipoint or at leastpoint-to-multipoint connectivity between one another which allowspoint-to-multipoint connectivity between external elements. Accordingly,traffic received by a port group 50 can be routed directly from aningress port 34 to a plurality of egress ports 34 without channelizationin the transport network 10.

Port groups 50 may be provisioned as simple port groups or as compositeport groups. In the simple port group configuration, each port 34 onlybelongs to a single port group 50. Private addresses can be supportedinside the simple port group configuration. A composite port groupincludes ports 34 which have membership in multiple port groups 50. Inthe composite port group case, private IP addressing is not supported.

The port groups 50 each define a transport element 52 withgeographically distributed ports 34. Each transport element 52 isassigned a unique global IP address for peering and protocol exchangeswithin and/or external to the transport network 10. As described in moredetail below, the transport elements 52 may implement a distributedarchitecture in which local processors control each of the ports 34 anda centralized processor controls the network element 52.

In particular embodiments, the transport elements may be transportrouters 60 interconnecting sets of subtending IP routers 14, transportEthernet switches 62 interconnecting sets of subtending Ethernetswitches 16, and transport Frame Relay switches 64 interconnecting setsof subtending Frame Relay switches 18. In addition, the transportelement 52 may interconnect two ports transparently, in which case theport group 50 is user protocol independent.

FIG. 2 illustrates details of the transport router 60 in accordance withone embodiment of the present invention. In this embodiment, thetransport router 60 comprises a simple port group 50 and acts as asingle network element within a customer's autonomous network.

Referring to FIG. 2, the transport router 60 includes geographicallydistributed ports 34 connected to external routers 14. The externalports 34 form a port group 50 with point-to-multipoint connectivitybetween the ports 34 as externally represented by the router 80.Accordingly, traffic from any one of the external routers 14 may berouted from an ingress port 34 directly to any number of the otherexternal routers 14 by router 80.

The transport router 60 includes a router identifier to peer with theexternal routers 14 and participate in reservation and other protocolexchanges. In a particular embodiment, the transport router 60 peerswith subtending routers 14 by using interior gateway protocols (IGP)such as OSPF, IS-IS, or RIP. The transport router 60 may peer using anexterior gateway protocol (EGP) or any other suitable protocol.

FIG. 3 illustrates details of the IPT node 30 in accordance with oneembodiment of the present invention. In this embodiment, the IPT node 30comprises an add/drop multiplexer (ADM) with modular building blocks tosupport a scalable, pay-as-you-grow architecture. Accordingly, thetransport network 10 owner may add functionality and incur cost based oncustomer demand. Functionality of the IPT node 30 may be implemented bylogic encoded in software and/or hardware media such as magnetic oroptical disks, application specific integrated circuits (ASIC), fieldprogrammable gate arrays (FPGAs), general purpose processors and thelike.

Referring to FIG. 3, the IPT node 30 includes one or morereceiver-transceiver pairs (RTP) 100 and a processing system 102interconnected by an internal Ethernet connection. As described in moredetail below, each RTP 100 includes one or more internal interfaces 104and one or more external interfaces 106. The internal interfaces arehigh-speed interfaces between the IPT nodes 30 while the externalinterfaces 106 are low-speed ports 34 accessible to external nodes. Theinternal and local interfaces 104 and 106 may each be implemented as oneor more discrete cards.

Within the transport network 10, a set of internal interfaces 104 of theIPT nodes 30 are connected together between ports 34 of a port group 50to form an FTS between the ports 34 and provide multipoint-to-multipointand/or point-to-multipoint connectivity. In particular, a multiplexer ofan internal interface 104 is connected to a demultiplexer of a nextinternal interface 104 in the FTS while a demultiplexer of the internalinterface 104 is connected to a multiplexer of a previous internalinterface 104 in the FTS. The FTSs are directionally-sensitive topreferentially route pass-through traffic over local ingress traffic. Inthis way, traffic for a transport element 52 is transported between aningress and egress port on an FTS with minimal delay across thetransport network 10.

The processing system 102 includes one or more central processing units(CPUs) 108. The CPUs 108 may each operate the IPT node 30 or a transportelement 52. A CPU 108 operating the IPT node 30 includes an operatingsystem and control functionality for the IPT node 30. A CPU 108operating a transport element 52 includes control functionality for thedistributed components of the transport element 52.

FIG. 4 illustrates details of the RTP 100 in accordance with oneembodiment of the present invention. In this embodiment, the internalinterface 104 is a high-speed interface that operates at substantially10 Gb/s. The external interface 106 is a low-speed packet over SONET(POS) interface that operates at 2.5 Gb/s or below.

Referring to FIG. 4, the internal interface 104 includes an opticalreceiver 110, a demultiplexer 112, a multiplexer 114, and an opticaltransmitter 116. The optical receiver is a 10 Gb/s receiver withoutSONET or package level knowledge. The optical receiver 110 performs theoptical to electrical signal conversion. The optical receiver 110 mayinclude an amplifier and may directly interface with a wave divisionmultiplex (WDM) system.

The demultiplexer 112 drops local traffic and inter RTP traffic as wellas buffers transit traffic. In a particular embodiment, thedemultiplexer 112 has a set of 155 Mb/s connections to interface cardsof the external interface 106. The demultiplexer 112 may also have 155Mb/s connections to interface cards of other RTPs 100.

The multiplexer 114 collects local traffic from the interface cards ofthe external interface 106 and through traffic from the demultiplexer112. The multiplexer 114 includes packet buffer, scheduler and insertioncontrol functionality.

The optical transmitter 116 is a 10 Gb/s transmitter without SONET orpackage level knowledge. The optical transmitter 116 may include anoptical amplifier. The optical transmitter 116 performs a conversionfrom an electrical signal to an optical signal and may interfacedirectly with a WDM system.

The external interface 106 include a plurality of low-speed interfacecards 120. The low-speed interface cards 120 send and receive traffic toand from the multiplexer 114 and demultiplexer 112, respectively. Thelow-speed interface cards 120 also provide connections between the FTSs.

The low-speed interface cards 120 are the main buffering point foringress and egress traffic of the transport network 10. Packet levelintelligence, including routing and protection mechanisms, are providedby the low-speed interface cards 120. If the transport network 10 usesan isolated addressing scheme, the low-speed interface cards 120 performNAT functionality.

FIG. 5 illustrates details of the processing system 102 in accordancewith one embodiment of the present invention. In this embodiment, thetransport network 10 includes an internal (IPTL1) layer and an external(IPTL2) layer. The processing system 102 provides a distributedarchitecture for the transport element 52. In particular, each port 34of a transport element 52 is locally managed with control processingperformed by a centralized processor.

Referring to FIG. 5, the processing system 102 includes four CPUs 108each configurable to operate the IPT node 30 or a transport element 52.The first CPU 140 manages the IPT node 30 and includes a simple networkmanagement protocol (SNMP) agent/internal network layer one (IPTL1)management information base (MIB) 142 for the IPT node 30. A commonmanagement information base (CMIB) 144 includes a model 146 of thetransport network 10 and slave models 148 for transport elements havinglocal ports. A database manager 150 manages the CMIB 144. An internaltransport network layer one (IPTL1) architecture 152 includes aninternal open shortest path first (IOSPF) instance 154 for discovery ofthe transport network 10. The IPTL1 architecture also includes controlcomponent subsystems 156.

In one embodiment, the IPT nodes 30 may comprise internal asymmetricconnections between and/or within RTPs 100. In this embodiment, eachnode may determine and advertise its own topology for use by other nodesand store the topology of other nodes for internal routing.

In a particular embodiment, the CPU 108 managing the IPT node 30determines the topology of the node by identifying the RTPs 100 of thenode and the local or other interfaces 106 between the RTPs 100.Location of the node in the network and external link connections mayalso be identified.

Based on the topology results, all possible, feasible or other suitableconnectivity between components of the IPT node may be identified usingIOSPF 154. The IOSPF 154 may weight each internal link using a lowweight for high speed, intra RTP 100 connections and a higher weight forlower speed inter RTP 100 connections. In one embodiment, the high speedlinks are operable to transport traffic at a rate of 5 Gb/s or higher,such as 10 Gb/s. Non-connected, or impossible links may be given a veryhigh weight to prevent selection. IOSPF is then run to determine allconnectivity between node components.

After determination of the internode topology, the topology isdistributed to other IPT nodes in the transport network. In oneembodiment, the intranode connectivity is encoded into and advertisedand/or flooded in opaque LSAs upon node activation or modification. Theopaque LSA provides a model of the node to other nodes in the network.It will be understood that the internal node topology may be otherwisesuitable modeled to other network nodes such that the nodes caninterpret the information and use it to determine routing paths throughthe network. In this embodiment, each IPT node 30 stores the topology ofthe other nodes in a local configuration or other suitable database. Apath label calculation may interact with the database to determinenormal, or working, and protect paths for traffic through the network.

In another embodiment, the RTPs 100 and/or components with interfacesmay be modeled as routers. In this embodiment, the router is a pointwithout latency between points with bandwidth restrictions. Internodetopology is identified by the RTP/interface connections. It will beunderstood that the topology of an asymmetric ITP node may be otherwisesimply determined without departing from the scope of the presentinvention.

The second CPU 160 is a master controller for a first transport element52 of the transport network 10. The second CPU 160 includes an SNMPagent/external network MIB 162 for the first transport element 52. ACMIB 164 includes a master model 166 of the layer two (IPTL2)architecture for the first transport element 52. A database manager 168manages the CMIB 166. The IPTL2 architecture 170 includes an OSPFinstance 172 for discovery of the network connected to the firsttransport element 52. The IPTL2 architecture also includes controlcomponent subsystems 174.

The third CPU 180 is a master controller for a second transport element52 of the transport network 10. The third CPU 180 includes an SNMPagent/external network MIB 182 for a second transport element 52. A CMIB184 includes the master model 186 of the IPTL2 architecture for thesecond transport element 52. A database manager 188 manages the CMIB184. The IPTL2 architecture 190 includes an OSPF instance 192 fordiscovery of the network connected to the second transport element 52.The IPTL2 architecture also includes control component subsystems 194.

The OSPF instances for each transport element discovers the topology forthe element and generates the master model. The model is thendistributed to the port controllers as slave models forpoint-to-multipoint connectivity within the port group of the transportelement. The fourth CPU 198 is unassigned to a particular transportelement 52 and may be idle or used to control lower layer functions.

In operation, layer one (IPTL1) learns the internal topology and doesnot exchange this information outside the transport network 10. Theinternal paths are learned using IPTL1 in order to route traffic betweenany two points within the network 10 regardless of the contents of thepackage. The traffic may be locally or externally generated. All IPTnodes 30 participate in IPTL1. Layer two (IPTL2) deals with the externaltopology for a transport router.

Each IPT node 30 is assigned a unique internal OSPF (IOSPF) routeridentifier. The transport network 10 runs IOSPF between the IPT nodes 30to provide normal and protection paths between ingress points of thenetwork. As a result, the transport network is modeled as a collectionof routers interconnected by point-to-point links.

As described in more detail below, path label calculation (PLC)interacts with the IOSPF in order to learn the transport network 10topology. Based on the learned topology, PLC determines the normal andprotection paths. PLC also addresses overlapping paths. After PLC haslearned the transport network topology, PLC signals IPTL2 to startrunning. When IPTL2 converges, OSPF is updated in the forwarding tablefor the corresponding transport element 52. PLC then populates thelook-up table for the ports 34 of the transport element 52.

FIG. 6 is a block diagram illustrating the distributed controlarchitecture for transportation routers 60 in an exemplary network. Theexemplary network includes a first IPT node 200, a second IPT node 202,a third IPT node 204, and a fourth IPT node 206.

The first IPT node 200 includes a first and second port for a firsttransport router, a first port for a second transport router, and afourth and fifth port for a third transport router. The first CPU 210includes control functionality for the first IPT node 200 as well asslave models of the first, second, and third transport routers forcontrolling the local ports. The second CPU 212 is a master controllerfor the first transport router.

The second IPT node 202 includes a third port of the third transportrouter and a third and fourth port of the second transport router. Thefirst CPU 220 includes control functionality for the second IPT node 202and slave models of the second and third transport routers forcontrolling the local ports. The second CPU 222 is a primary controllerfor the third transport router.

The third IPT node 204 includes the fourth port of the first transportrouter, a second port of the second transport router, and a first andsecond port of the third transport router. The first CPU 230 comprisescontrol functionality for the third IPT node 204 and slave models of thefirst, second, and third transport routers for managing the local ports.The second CPU 232 includes a master controller for the second transportrouter.

The fourth IPT node 206 includes a third port of the first transportrouter and a fifth port of the second transport router. The first CPU240 includes control functionality for the fourth IPT node 206 and slavemodels of the second transport routers for controlling the local ports.In this way, each IPT node and ports of the IPT node are locallymanaged. The distributed transport elements are managed by a centralizedcontroller on any one of the IPT nodes.

FIG. 7 illustrates the IPTL1 architecture 250 in accordance with oneembodiment of the present invention. FIG. 8 illustrates the IPTL2architecture 260 in this embodiment in which the transport network 10uses a transport label to efficiently transport traffic in the network10. OSPF uses opaque link state advertisements (OLSAs) in order todiscover the external network topology.

Referring to FIG. 7, the functionality of the PLC 252 is based onwhether the processor is managing an instance of IOSPF. An IPT node 30will have only one instance of IOSPF, but each processor will have aninstance of PLC 252. The PLC 252 instance associated with IOSPF builds alocal configuration database (LDB) from IPTL1 and IPTL2 provisionvalues, creates the OLSA entry from the configuration of IPTL1, tunnelsthe OLSA entry to IOSPF, retrieves the OLSA database from IOSPF uponIOSPF's notification of convergence, synchronizes the OLSA database withits PLC peers within an IPT node, signals IPTL2 to start by adding thetransport router's port IP address, the multicast host, and transportrouter's IP address to the port prefix table and adding the CPU's labelto the transport table of the port. The PLC 252 also receives the IPTL2forwarding table (IP forwarding table), populates the prefixes, thetransport labels and the destinations mapping tables for the ports ofthe IPTL2.

The PLC 252 receives fault signal from a fault manager which indicatethe link failure identifier. In response to a link failure, the PLC 252determines which label is effected by the link failure and marks thelabel as invalid in the transport label's table per port. If the linkidentifier is local, the OLSA conveys the failure and hands failureprocessing over to IOSPF.

The PLC 252 also translates an internal reservation protocol (RSVP)request on a normal path. The internal RSVP specifies the ingress andegress ports. The normal path includes a control path and a data path. Acontrol path is a list of IPT nodes 30 to be traversed from a source toa destination. The data path is a list of high speed and slow speedlinks to be traversed between the source and the destination. If theinternal RSVP succeeds in making a reservation on the normal path, itindicates to the PLC 252 the new QoS of the path. The PLC 252 updatesthe QoS of the normal transport label for the port 34. The same processoccurs for the protection path. If the port 34 is not local to the PLC252, the PLC 252 tunnels the information to the PLC 252 where the portresides to do the update. Further information regarding the internalreservation process is described in co-owned U.S. patent applicationentitled “System and Method for Opaque Application Object Transport”,filed Jun. 6, 2000.

The PLC 252 further supports a proprietary MIB for port lookup table andreceives requests from MPLS. The requests include an IP destinationprefix and an ingress port. The PLC 252 returns the pointers of thenormal and protection transport labels and a next-hop IP address of thesubtending router 14. The PLC 252 supports a device driver API to updatethe forwarding table in the port and supports a label translator toreach any point in the transport network 10.

The PLC 252 instance not associated with IOSPF builds a localconfiguration database (LDB) from IPTL1 and IPTL2 provisioned values,synchronizes the OLSA database with its IOSPF's PLC peers within an IPTnode, signals IPTL2 to start by adding the transport router's port IPaddress, the multicast host, and transport router IP address to the portprefix table and adding the CPU's label to the transport table of theport, populates the prefixes, the transport labels, and the destinationsmapping tables for the ports of the IPTL2.

The PLC 252 also receives fault signal from a fault manager which willindicate the link failure identifier. In this case the PLC 252determines which label has been effected by the link failure and marksthe label as invalid in the transport label's table per port.

The PLC 252 further translates an external IP address to IPTL2 to anegress port for external RSVP, receives signals from a PLC 252associated with IOSPF to update the local port and receives an internalRSVP request on a normal path. As previously described, the internalRSVP will specify the ingress and egress ports. The normal path includesa control path and a data path. The control path is a list of IPT nodes30 to be traversed from a source to a destination. The data path is alist of high speed links and low speed links to be traversed between thesource and the destination. If the internal RSVP has succeeded in makingreservation on the normal path, it indicates to the PLC 252 the newquality of service (QoS) of the path. The PLC 252 updates the QoS of thenormal transport label for the port. The same process occurs forprotection path. The PLC 252 also supports a device driver API to updateforwarding table in ports and supports a label translator to reach anypoint in an transport network 10. To perform the necessary functions,IOSPF will include an API to permit the PLC 252 to pass the OLSA to theIOSPF, signal the PLC to retrieve OLSA database, modify OSPF link statedatabase's structure to store and flood OLSA.

Referring to FIG. 8, the IPTL2 architecture 260 comprises the topologyfor the transport router 60. The transport router manages the ports 34in its ports group 50. The subtending routers 14 view the transportrouter 60 as a single router. The transport router 60 reacts to bothexternal and internal changes in topology, which triggers updatesbetween the subtending routers 14 and the transport router 60. Changesinside the transport network 10 that do not impact the states of theport 34 are not reported to the subtending routers 14.

As previously described, a master transport router instance resides in asingle processor 262 within the transport network 10. Slave processors264 resides on each transport node 30 including a port 34 for thetransport router 60. Each processor 262 and 264 associated with thetransport router 60 has a port group communication module 266.

A TCP connection is established between the transport routers instanceand the ports instances. This connection is used to traffic control databetween the transport router 60 and the subtending routers 14. Thecommunication instance for the transport router 60 monitors the statesof the transport routers ports 34 via the TCP connection with the portsinstance, downloads a forwarding table upon notification from therouters OSPF, requests from the PLC 252 to translate a port 34 to atransport label, interacts with CMP 268 to send and receive packets, andtunnels the management's control packets to the transport routers ports34. The ports communication instance establishes TCP connections withthe transport router 60, tunnels all control packets to the transportrouter 60, request from the PLC 252 to translate a port 34 to atransport label, receives a forwarding table from the transport router60 and downloads a forwarding table to the PLC 252.

FIG. 9 illustrates a method for determining and advertising anasymmetric intranode topology within the transport network 10 inaccordance with one embodiment of the present invention. The methodbegins at step 300 in which the IPT node 30 is configured to establishRTPs 100 and interfaces between the RTPs 100. Next, at step 302,connections between components within the IPT node 30 are identified. Aspreviously described, the connections may be identified by determiningthe RTPs 100 and their corresponding links, interfaces between the RTPs100, the location of the node in the transport network 10, and externallink connections of the node.

Proceeding to step 304, all possible or other suitable connectivitybetween components of the IPT node 30 are determined based on theintranode connections. In one embodiment, the possible connectivity isdetermined by weighting the links based on whether they are intra RTPlinks, inter RTP links or non-connected links and running IOSPF on theweighted links.

Next, at step 306, the node topology is distributed in the transportnetwork 10. As previously described, the node topology may be encodedinto and distributed in opaque LSAS. At step 308, the node topology isstored at each node in the transport network 10. The node topologies maybe used to determine FTSs and minimum low speed hops between FTSs forpaths across the network.

FIG. 10 illustrates a method for provisioning transport elements 52 inthe transport network 10 in accordance with one embodiment of thepresent invention. The method begins at step 350 in which connectionsare provisioned between the IPT nodes 30. The connections define theFTSs within the transport network 10. At step 352, addresses for eachtransport elements 52 are defined within the address space for the IPTnetwork 10.

Proceeding to step 354, the internal topology of the transport networkis discovered. At step 356, transport elements 52 are defined within thetransport network 10. The transport elements 52 each comprise a portgroup 50 and may be a transport router, transport Ethernet switch, ortransport Frame Relay switch. At step 358, topology of the transportelements 52 and connected external nodes are discovered.

Next, at step 360, the transport elements 52 each peer with thesubtending routers 14 or other external nodes. At step 362, thetransport elements 52 generate routing tables for receiving andtransmitting packets to and from the external network and within thetransport network 10. In this way, the transport elements 52 are freelydefined within the transport network 10 to match the topology of thenetwork 10 to needs of customers.

FIG. 11 illustrates a method for defining a transport element 52 in thetransport network 10 in accordance with one embodiment of the presentinvention. The method begins at step 400 in which a master, or primaryprocessor for the transport element 52 is assigned within the transportnetwork 10. As previously described, the master processor controls thetransport element 52 directly and through slave processors local to eachof the ports 34. Next, at step 402, ports 34 are identified and assignedto the transport element 52.

Proceeding to step 404, a local processor is assigned or otherwiseprovided for each port 34 of the transport element 52. In oneembodiment, the local processor by default is a master processor foreach corresponding IPT node 30. At step 406, an identifier is assignedto the transport element 52 to allow the transport element 52 toparticipate in protocol exchanges and otherwise appear as a singleelement to external nodes.

FIG. 12 illustrates a method for generating routing tables for atransport element 52 in accordance with one embodiment of the presentinvention. The method begins at step 450 in which a routing informationbase (RIB) is generated by a master processor for a transport element52. The RIB is generated based on the IPTL1 and IPTL2 architectures.

At step 452, the RIB is distributed to each port 34 of the transportelement 52. At step 454, a forwarding information base (FIB) isgenerated at each port 34 based on the RIB. The ports 34 use the RIB toprocess traffic received from the transport network 10 or the externalnetwork 12. Step 454 leads to the end of the process by which routinginformation is centrally generated and distributed for the transportelement 52.

FIG. 13 illustrates a method for processing through traffic in atransport element 52 in accordance with one embodiment of the presentinvention. The method begins at step 500 in which an IP packet isreceived at an ingress port 34 of a transport element 52. At step 502, atransport label is generated based on the IP address using the FIB forthe transport element 52.

Proceeding to step 504, the transport label is added to the IP packet togenerate an internal packet. At step 506, the internal packet istransported to an egress port 34 of the transport element 52 onhigh-speed links based on the transport label.

Next, at step 508, the transport label is removed from the IP packet atthe egress port 34. At step 510, the IP packet is transmitted to anexternal destination element. Step 510 leads to the end of the processby which IP packets are transmitted across the transport network 10 onhigh speed links using transport labels overhead.

Although the present invention has been described with severalembodiments, various changes and modifications may be suggested to oneskilled in the art. It is intended that the present invention encompasssuch changes and modifications as fall within the scope of the appendedclaims.

1. A method for providing an internal topology of a node within anetwork, comprising: determining asymmetric connections between receivertransmitter pairs (RTPs) in a network node; the RTPs each comprisingintra RTP connections between internal RTP components, the intra RTPconnections having a higher speed than the asymmetric connectionsbetween the RTPs, wherein the internal RTP components comprise anoptical receiver and an optical transmitter for interfacing with awavelength division multiplex (WDM) system; determining an intranodeconnectivity between the RTPs based on the asymmetric connections;distributing a model of the node indicative of the intranodeconnectivity to a disparate node in a network with the node; and usingthe model at the disparate node in determining a routing path throughthe network.
 2. The method of claim 1, wherein the RTPs comprise lowerspeed interfaces to external nodes coupled to the network.
 3. The methodof claim 1, further comprising determining all possible internodeconnectivity between the RTPs based on the asymmetric connections. 4.The method of claim 1, further comprising distributing the model usingopaque link state advertisements (LSAs).
 5. The method of claim 1,wherein the network comprises a private network.
 6. The method of claim1, further comprising determining internode connectivity between theRTPs by assigning weights to the asymmetric connections based on theirspeed.
 7. The method of claim 1, further comprising: assigning a firstweight for higher speed connections and a second higher weight for lowerspeed connections to generate weighted connections; and utilizing openshortest path first on the weighted connections at the disparate node todetermine the routing path through the network.
 8. A system forproviding an internal topology of a node within a network, comprising:means for determining asymmetric connections between receivertransmitter pairs (RTPs) in a network node; the RTPs each comprisingintra RTP connections between internal RTP components, the intra RTPconnections having a higher speed than the asymmetric connectionsbetween the RTPs, wherein the internal RTP components comprise anoptical receiver and an optical transmitter for interfacing with awavelength division multiplex (WDM) system; means for determining anintranode connectivity between the RTPs based on the asymmetricconnections; means for distributing a model of the node indicative ofthe intranode connectivity to a disparate node in a network with thenode; and means for using the model at the disparate node in determininga routing path through the network.
 9. The system of claim 8, whereinthe RTPs comprise lower speed interfaces to external nodes coupled tothe network.
 10. The system of claim 8, further comprising means fordetermining all possible internode connectivity between the RTPs basedon the asymmetric connections.
 11. The system of claim 8, furthercomprising means for distributing the model using opaque link stateadvertisements (LSAs).
 12. The system of claim 8, wherein the networkcomprises a private network.
 13. The system of claim 8, furthercomprising means for determining internode connectivity between the RTPsby assigning weights to the asymmetric connections based on their speed.14. The system of claim 8, further comprising: means for assigning afirst weight for higher speed connections and a second higher weight forlower speed connections to generate weighted connections; and means forutilizing open shortest path first on the weighted connections at thedisparate node to determine the routing path through the network.
 15. Asystem for providing an internal topology of a node within a network,comprising: logic encoded in media; and the logic operable to determineasymmetric connections between receiver transmitter pairs (RTPs) in anetwork node, the RTPs each comprising intra RTP connections betweeninternal RTP components, the intra RTP connections having a higher speedthan the asymmetric connections between the RTPs, wherein the internalRTP components comprise an optical receiver and an optical transmitterfor interfacing with a wavelength division multiplex (WDM) system, thelogic further operable to determine an intranode connectivity betweenthe RTPs based on the asymmetric connections, to distribute a model ofthe node indicative of the intranode connectivity to a disparate node ina network with the node and to use the model at the disparate node indetermining a routing path through the network.
 16. The system of claim15, wherein the RTPs comprise lower speed interfaces to external nodescoupled to the network.
 17. The system of claim 15, the logic furtheroperable to determine all possible internode connectivity between theRTPs based on the asymmetric connections.
 18. The system of claim 15,the logic further operable to distribute the model using opaque linkstate advertisements (LSAs).
 19. The system of claim 15, wherein thenetwork comprises a private network.
 20. The system of claim 15, thelogic further operable to determine internode connectivity between theRTPs by assigning weights to the asymmetric connections based on theirspeed.
 21. The system of claim 15, the logic further operable to assigna first weight for higher speed connections and a second higher weightfor lower speed connections to generate weighted connections and toutilize open shortest path first on the weighted connections at thedisparate node to determine the routing path through the network.